Gas burner apparatus

ABSTRACT

An improved gas burner apparatus of the type having a hollow inner liner supported within an outer shell, such that combustion air injected between the inner liner and the outer shell travels in a generally helical path to the rear end portion of the inner liner and thoroughly mixes with fuel injected into the end of the outer shell, the fuel and combustion air being mixed and burned generally within the inner liner. The improved gas burner apparatus of the present invention includes a noise abatement apparatus secured to the rear end of the inner liner to diffuse a portion of the combustion air thereby substantially eliminating undesirable noise encountered during operation of the gas burner apparatus, and a flame protection apparatus encompassing the opening for injecting fuel into the outer shell to diffuse a portion of the combustion air thereby preventing the pilot flame from being blown-out.

ilnited States Patent I Arenson l lMarch 13, 1973 [73] Assignee: Black, Sivalls & Bryson, lnc.,

Oklahoma City, Okla.

[22] Filed: June 3, 1971 [21] Appl. No.: 149,716

[52] U.S.Cl. ..43l/l14,431/l58,431/238, 431/353 [51] Int. Cl.... ..F23d 15/02 [58] Field of Search ..431/114,l58, 182, 238, 351-354 [56] References Cited 2 UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 244,860 7/1960 Australia ..43l/353 Primary ExaminerCarroll B. Dority, Jr. Attorney-Dunlap, Laney, Hessin & Dougherty [57] ABSTRACT An improved gas burner apparatus of the type having a hollow inner liner supported within an outer shell, such that combustion air injected between the inner liner and the outer shell travels in a generally helical path to the rear end portion of the inner liner and thoroughly mixes with fuel injected into the end of the outer shell, the fuel and combustion air being mixed and burned generally within the inner liner. The improved gas burner apparatus of the present invention includes a noise abatement apparatus secured to the rear end of the inner liner to diffuse a portion of the combustion air thereby substantially eliminating undesirable noise encountered during operation of the gas burner apparatus, and a flame protection apparatus encompassing the opening' for injecting fuel into the outer shell to diffuse a portion of the combustion air thereby preventing the pilot flame from being blown-out.

III/III 1. GAS BURNER APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to improvements in gas burner apparatus and, more particularly, but not by way of limitation, to a noise abatement apparatus and a flame protection apparatus for a gas burner.

2. Description of the Prior Art A gas burner apparatus is disclosed in detail in US. Pat., No. 3,265,113, which is assigned to the assignee of the present invention, having an outer shell and a coaxial inner liner, wherein pressurized combustion air is injected into the space generally between the inner liner and the outer shell, and fuel is injected into a space generally between the rear end of the inner liner and the rear end of the outer shell. The combustion air injected into the gas burner apparatus travels in a helical path toward the fuel injection portion of the gas burner apparatus generating a vortex which results in a thorough mixing of the fuel and the combustion air, the mixed fuel and combustion air being burned generally within the interior of the innerliner.

The patent discloses a plurality of radially extending plates disposed generally within the fuel entrance passageway, the radially extending plates being provided to disturb the combustion air vortex thereby preventing the blowing out of the pilot flame. The gas burner apparatus described in the patent also included noise plates disposed generally adjacent the rear end of the outer shell and spaced generally along the inner periphery of the outer shell, the noise plates being provided to reduce the noise level of the gas burner apparatus during the operation thereof.

Although the radially extending plates did, to some extent, reduce the problem of the pilot flame being blown-out by the combustion air vortex, it has been found that, in many instances, the plates were not suffi cient to prevent the blowing out of the flame, particularly in those instances wherein the flame was to be reduced while attempting to maintain the combustion air flow through the gas burner substantially at a maximum. It was therefore found necessary toinclude various control devices to reduce the flow of combustion air into the gas burner in proportion to the cut-back in fuel supplied to the burner during operational cycles of the gas burner apparatus. It has also been found that, even in those instances where such control devices have been provided, that the combustion air vortex created within the gas burner apparatus, in many instances, was still of a sufflcient velocity to blow the pilot flame out, thereby requiring an automatic or a manual re-igniting sequence. It has also been found that, although the plates disposed about the inner periphery of the outer shell did, to some extent, reduce the noise level of the gas burner apparatus, that in many applications the undesirable noise level of the gas burner apparatus still remained significantly high.

SUMMARY OF THE INVENTION The present invention contemplates an improved gas burner apparatus including: a hollow outer shell, having a front end and a rear end. A front end wall is secured to the front end, and a rear end wall, having an opening formed therethrough, is secured to the rear end of the outer shell, thereby closing the rear end. A

hollow inner liner, having a front end and a rear end, is supported within the hollow portion of the outer shell and is spaced from the outer shell to form an air passageway between the outer shell and the inner liner, the front end of the inner liner extending through the front end wall and rear end of the inner liner being spaced a predetermined distance from the rear end wall. An air inlet is formed in the outer shell and is spaced from the rear end thereof for admitting combustion air into the air passageway. The gas burner apparatus also includes means for injecting fuel through the opening in the rear end wall and into the hollow portion of the outer shell, generally between the rear end of the inner liner and the rear end wall, the fuel and combustion air being mixed and burned generally within the hollow portion of the inner liner. A noise abatement apparatus, having an aperture means formed therethrough, is secured to the rear end of the inner liner and extends a distance therefrom generally between the rear end of the inner liner and the rear end wall, to diffuse a portion of the combustion air thereby substantially eliminating undesirable noise during the operation of the gas burner apparatus. A flame protection apparatus, having an aperture means formed therethrough is secured to a portion of the rear end wall, and substantially encompasses the opening through the rear end wall to diffuse a portion of the combustion air thereby preventing the combustion air from blowing out the pilot flame.

An object of the invention is to provide gas burner apparatus having a substantially reduced noise level during the operation thereof.

Another object of the invention is to provide a gas burner apparatus wherein the pilot flame is protected from being blown-out during the operation thereof.

An additional object of the invention is to provide a gas burner apparatus utilizing injected, pressurized combustion air, wherein the heat output of the gas burner apparatus can be controlled independent of the flow of injected, pressurized combustion air.

A further object of the invention is to provide a noise abatement apparatus and a flame protection apparatus for utilization in a gas burner, which is economical in construction and operation.

One other object of the invention is to provide a more efficient gas burner apparatus which is economical in construction and operation.

Other objects and advantages of the invention will be evident from the following detailed description when read in conjunction with the accompanying drawings which illustrate a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. -1 is a partial sectional, partial diagrammatical view of a gas burner apparatus constructed in accordance with the present invention.

FIG. 2 is an enlarged view of one end portion of the gas burner apparatus of FIG. 1, showing the noise abatement apparatus and the flame protection apparatus in greater detail.

FIG. 3 is an end view of the noise abatement apparatus of the gas bumer apparatus of FIG. 1.

FIG. 4 is an end view of the flame protection apparatus of the gas burner apparatus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in detail, and to FIG. 1 in particular, shown therein and designated by the general reference numeral is a gas burner which includes; a hollow outer shell 12, having a front end 14 and a rear end 16; and a hollow inner liner 18, having a front end 20 and a rear end 22, which is supported generally within the hollow portion of the outer shell 12. A front end wall 24 is secured to the front end 14 of the outer shell 12, thereby closing the front end portion 14, as shown in FIG. 1. A rear end wall 26 is secured to the rear end portion 16 of the outer shell 12, thereby closing the rear end 16.

The the inner liner 18 is supported withing the hollow portion of the outer shell 12 and spaced a distance therefrom about the entire outer periphery of the inner liner 18, to form an air passageway, designated in FIG. 1 by the reference numeral 28, generally between the inner liner l8 and the outer shell 12.

An air inlet 30 is formed in a portion of the outer shell 12 and, more particularly, the air inlet 30 is constructed and connected to the outer shell 12 to direct pressurized combustion air into the air passageway 28, generally tangential to the inner periphery of the outer shell 12, the air inlet 30 being preferably volute-shaped to increase the rotational flow and the energy of the pressurized combustion air entering the outer shell 12 via the air inlet 30. It should be noted that the term combustion air, as used above and below, denotes a fluid product which is mixed with a fuel during the operation of the gas burner apparatus 10 and may be air or oxygen for example.

In a preferred form, a rearward end portion 32 of the inner liner 18 is frusto-conically shaped, converging toward the rear end thereof. A forward end portion 34 of the inner liner l8 converges toward the front end 20 thereof and, in a preferred form, the forward end portion 34 is also frusto-conically shaped and converges in such a manner that an elongated narrow outlet 36 is formed at the front end 20 of the inner liner 18.

As shown in FIG. 1, the front end 20 of the inner liner 18 extends through the front end wall 24, and the inner liner 18 is supported within the outer shell 12 such that the rear end 22 thereof is spaced a distance 38 from a center line through rear end wall 26, as shown in FIG. 2, which in a preferred form, is at least one-half the diameter of the hollow portion of the inner liner 18, generally adjacent the rear end 22 thereof. The outer shell 12 is preferably shaped such that the inner liner 18 and the outer shell 12 are coaxially positioned.

A burner assembly 40 is supported near the rear end wall 26 and includes: a pilot gas line 42 and a main gas line 44. An opening 46 is formed through the rear end wall 26 and the pilot gas line 42 and the main gas line 44 communicate with an ignition space 48 via the opening 46. The burner assembly 40 also includes an ignition assembly 50 which, in one form, may be a spark plug type ignition device. The gas burner apparatus 10 is thus constructed such that combustion air is injected into the hollow portion of the outer shell 12 or, more particularly, into the air passageway 28 via the air inlet 30 and follows a helical path toward the ignition space 48 generally between the rear end wall 26 and the rear end 22 of the inner liner 18, in such a manner that an angular velocity is imparted to the combustion air.

The combustion air creates an air vortex generally within the ignition space 48, and the combustion air is mixed with the fuel gas entering the ignition space 48 via the main gas line 44. The diverging-converging shape of the inner liner 18 causes the helically flowing air to create a vortex and the combustion product flows generally toward the outlet or front end 20 of the inner liner 18, and is reversed into the center of the inner liner 18 to provide complete combustion of the fuel products and to insure that the combustion is completed within the inner liner 18. A gas burner, which operates in a manner generally as described above, is disclosed in detail in the U. S. Pat., No. 3,265,113, and therefore a detailed description of the combustion process which occurs within this type of apparatus is not given herein.

As shown in FIGS. 1 and 2, a noise abatement apparatus 54 is secured to the rear end 22 of the inner liner 18, and extends a distance therefrom generally between the rear end 22 of the inner liner l8 and the rear end wall 26. The noise abatement apparatus 54 has an outer periphery 56 and opposite ends 58 and 60 and, as shown more clearly in FIGS. 2 and 3, the noise abatement apparatus 54 is, in a preferred form, cylindrically shaped, having an outer diameter 61. It should be particularly noted that the diameter 61 is substantially equal to the inner diameter of the inner liner 18, generally near the rear end 22 thereof, for reasons to be made more apparent below.

As shown in FIGS. 2 and 3, a plurality of stops 62 are secured to the outer periphery 56 of the noise abatement apparatus 54, each stop 62 extending a distance radially from the outer periphery 56 of the apparatus 54 and being spaced circumferentially thereabout. As shown more clearly in FIG. 2, each stop 62 is spaced a distance 64 from the end 58 of the noise abatement apparatus 54. The outer periphery 56 of the apparatus 54 is shaped to conform to the inner periphery of the inner liner 18, generally near the rear end 22 thereof so that the apparatus 54 can be slid axially, inwardly into the hollow portion of the inner liner 18, to a position wherein each stop 62 engages a portion of the rear end 22 of the inner liner 18 to limit the inward movement of the apparatus 54 and to position the apparatus 54 in an assembled position with respect to the inner liner 18, as shown in FIGS. 1 and 2. In the assembled position of the noise abatement apparatus 54, each stop 62 is secured to the rear end 22 of the inner liner 18, such as by tack welding thereto.

The axial width of the noise abatement apparatus 54 is sized such that the apparatus extends a distance 66 beyond the rear end 22 of the inner liner 18, generally toward the rear end wall 26, in an assembled position thereof, as shown in FIG. 2. As shown in FIGS. 1 and 2, a plurality of apertures 70 are formed through the outer periphery 56 of the apparatus 54, the apertures 70 being spaced about the outer periphery 56 and positioned to diffuse the combustion air passing therethrough, and thereby diffusing that portion of the combustion air vortex created generally about and near the rear end 22 of the inner liner 18. In a preferred form, it has been found that the noise abatement apparatus 54 should preferably be sized such that the distance 66 is approximately one-fourth of the distance 38, generally between the rear end 22 of the inner liner 18 and the center line of the rear end wall 26. In one form, it has been found that apertures having a threeeighths inch diameter and spaced about the outer periphery 56 on one-half inch centers provide adequate diffusion. In this manner the noise abatement apparatus 54 functions to diffuse a significant portion of the air vortex causing the undesirable noise during the operation of the gas burner 10, yet does not substantially interfere with the combustion air flow pattern through the gas burner so as to have any deleterious effect on the combustion and flame pattern therein.

As shown in FIGS. 1 and 2, a flame protection apparatus 74, having an outer periphery 76 and opposite ends 78 and 80, is disposed adjacent the rear end wall 26, and positioned thereon to encompass the opening 46 through the rear end wall 26. The flame protection apparatus 74 is, in a preferred form, cylindrically shaped, as shown in FIG. 4. The flame protection apparatus 74 includes a plurality of apertures 82 formed through the outer periphery 76 thereof and has a diameter 84 formed by the outer periphery 76.

As shown in FIG. 2, the end 80 of the flame protection apparatus 74 is secured to the rear end wall 26 and the apparatus 74 extends a distance 86 from the rear end wall 26, generally toward the rear end 22 of the inner liner 18. In a preferred form, the distance 86 is 35 to 40 percent of the dimension 38; the diameter 84 of the apparatus 74 is approximately 50 percent of the inner diameter of the inner liner 18 generally near the rear end 22 thereof, or, in other words, approximately equal to 50 percent of the diameter 61; and the apertures 82 have a three-eighths inch diameter and are spaced about the outer periphery 76 on one-half inch centers. In this configuration it has been found that the flame protection apparatus 74 diffuses a sufficient portion of the combustion air vortex to prevent the pilot flame from being blown out, and yet the flame protection apparatus 74 does not interfere with the combustion air flow pattern through the gas burner apparatus 10 so as to have any deleterious effect on the combustion or flame pattern therein.

OPERATION OF THE PREFERRED EMBODIMENT During the operation of the gas burner 10, the pressurized combustion air is injected through the air inlet 36) into the air passageway 28 between the inner liner 18 and the outer shell 12, the air being forced into the air passageway 28 generally tangentially from a compressor or the like (not shown). The air fills the air passageway 28 and is moved in a helical path about the inner liner 18 generally toward the rear end wall 26 of the gas burner 10 to create a low pressure area generally near the opening 46 or, in other words, generally near the fuel injection point, thereby allowing the use of low pressure fuel, and the combustion air vortex thus created causes a rapid mixing of the fuel and combustion air in the ignition space 48. The flow is then directed into the inner liner 18 generally toward the outlet 36, where a reversal of flow occurs due to the convergence of the forward end portion 34 of the inner liner 18, thereby providing thorough mixing and complete combustion of the fuel and air within the inner liner 18. It should also be noted that an excess of combustion air exists in the hollow portion of the outer shell 12 which is utilized to cool the inner liner 18, thereby allowing a substantial portion of the gas burner apparatus 10 to be constructed of a metal and thus eliminating excessive utilization of various refractory materials in the construction thereof.

A portion of the combustion air vortex existing in the ignition space 48 is diffused by the noise abatement apparatus 54. More particularly, a portion of the combustion air vortex in the ignition space 48 generally near the rear end 22 of the inner liner 18 is diffused by the noise abatement apparatus 54, during the operation of the gas burner apparatus 10. It has been found that the velocity of the combustion air and the combustion air vortex per se existing generally near the rear end 22 of the inner liner 18 has contributed substantially to the high noise level, common in gas burners of a design similar to that described above with respect to the gas burner 10. Therefore, the noise abatement apparatus 54 is positioned on the inner liner 18 to substantially diffuse the portion of the combustion air vortex which contributes to the undesirable noise level thereby substantially eliminating the noise level of the gas burner 10, without substantially interfering with the efficiency of the gas burner 10. The flame protection apparatus 74 is positioned in the ignition space 48 to diffuse a substantial portion of the combustion air vortex generally near the opening 46 in the rear end wall 26 to prevent the combustion air from blowing out the pilot flame during the operation of the gas burner 10, in such a manner that the flame protection apparatus 74 does not interfere with the efficiency nor the desirable operational characteristics of the gas burner apparatus 10.

In most installations, the gas burner apparatus 10 is utilized to provide heat for a process fluid, and the amount of heat being provided by the gas burner apparatus 10 at any particular instant is controlled by various process characteristics. It thus becomes necessary, in many instances, to cycle the operation of the gas burner apparatus 10 or, in other instances, to reduce the amount of heat being provided by the gas burner apparatus 10 at a particular time. During such times when the gas burner apparatus 10 is cut-off or the heat being provided thereby is substantially reduced, it is desirable, in most instances to maintain the flow of combustion air through the gas burner apparatus 10 at or near a maximum, thereby permitting the combustion air to be utilized to cool the process fluid.

Utilizing the flame protection apparatus 74, constructed in a manner described above, the flame provided via the gas burner apparatus 10 can be effectively controlled, independent of the combustion air flow through the air inlet 30. In other words, the heat output of the gas burner apparatus 10 can be controlled over a wide range while leaving the combustion air flow to the gas burner apparatus 10 at or near a predetermined maximum flow leveLDuring those times when the heat output is reduced, the flame protection apparatus 74 substantially prevents the combustion air from blowing out the pilot flame, thereby permitting the gas burner apparatus 10 to be utilized more efiiciently in an overall process.

It should also be noted that the utilization of the flame protection apparatus 74 substantially eliminates the need for a large number of control components, which in the past have been utilized to proportionately control the flow of the combustion air into the gas burner apparatus with respect to the amount of heat being supplied via the gas burner apparatus 10.

The gas burner apparatus 10 thus provides a gas burner which can be more economically and efficiently operated and which will operate in a more efficient manner in cooperation with a particular process. The gas burner apparatus 10 can thus be constructed in a more economical manner, and will operate at a substantially reduced noise level and in such a manner that the maintaining of the pilot flame is virtually assured.

Changes may be made in the construction and the arrangement of the various parts or the elements as disclosed herein without departing from the spirit or scope of the invention as defined in the following claims:

What is claimed is:

1. A gas burner apparatus, comprising:

a hollow outer shell having a front end and a rear end;

a front end wall secured to the front end of the outer shell, thereby closing the front end;

a rear end wall, having an opening formed therethrough, secured to the rear end of the outer shell, thereby closing the rear end;

a hollow inner liner, having a front end and a rear end, the inner liner supported within the hollow portion of the outer shell and being spaced from the outer shell to form an air passageway between the outer shell and the inner liner, the front end of the inner liner extending through the front end wall and rear end of the inner liner being spaced a predetermined distance from the rear end wall;

an air inlet formed in the outer shell and spaced from the rear end thereof for admitting combustion air into the air passageway;

means for injecting fuel through the opening in the rear end wall and into the hollow portion of the outer shell, generally between the rear end of the inner liner and the rear end wall, the fuel and combustion air being mixed and burned generally within the hollow portion of the inner liner;

a noise abatement apparatus, including an annular member having perforations about its periphery and, secured to the rear end of the inner liner and extending a distance therefrom generally between the rear end of the inner liner and the rear end wall, to diffuse a portion of the combustion air thereby substantially eliminating undesirable noise during the operation of the gas burner apparatus; and

pilot flame protection apparatus, an annular member having perforations about its periphery secured to a portion of the rear end wall, the flame protection apparatus substantially encompassing the opening through the rear end wall to diffuse a portion of the combustion air thereby preventing the combustion air from blowing out said pilot flame.

2. The gas burner apparatus of claim 1 where the inner liner includes, a frusto-conical section converging toward the rear end thereof and a frusto-conical section converging toward the front end thereof; and wherein the outer shell is defined further as being shaped such that the inner liner and the outer shell are coaxially positioned.

3. The gas burner apparatus of claim 1 wherein the rear end of the inner liner is defined further as being spaced a distance from the rear end wall, the distance being at least one-half the diameter of the hollow portion of the inner liner, generally adjacent the rear end thereof.

4. The gas burner apparatus of claim 1 wherein the air inlet is defined further as being volute shaped to provide tangential combustion air into the air passageway.

5. The gas burner apparatus of claim 1 wherein the noise abatement apparatus is defined further as extending a distance from the rear end of the inner liner, the distance being substantially'equal to one-fourth of the distance between the rear end of the inner liner and the rear end wall.

6. The gas burner apparatus of claim 1 wherein the noise abatement apparatus is defined further as being generally cylindrically shaped, the diameter of the outer periphery of the noise abatement apparatus being sized to be slid into the hollow portion of the inner liner, generally adjacent the rear end of the inner liner.

7. The gas burner apparatus of claim 6 wherein the noise abatement apparatus is defined further to include: a plurality of stops, each stop being secured to a portion of the outer periphery of the noise abatement apparatus and extending a distance radially therefrom, each stop engaging a portion of the rear end of the inner liner to position the noise abatement apparatus in an assembled position within the hollow portion of the inner liner.

8. The gas burner apparatus of claim 1 wherein the flame protection apparatus is defined further as extending a distance from the rear end wall generally toward the rear end of the inner liner, the distance being generally between 35 and 40 percent of the distance between the rear end of the inner liner and rear end wall.

9. The gas burner apparatus of claim 1 wherein the flame protection apparatus is defined further as being generally cylindrically shaped, the diameter of the flame protection apparatus being approximately equal to 50 percent of the diameter of the hollow portion of the inner liner, generally adjacent the rear end thereof.

10. A gas burner apparatus, comprising:

a hollow outer shell having a front end and a rear end;

a front end wall secured to the front end of the outer shell, thereby closing the front end of the outer shell;

a rear end wall secured to the rear end of the outer shell, thereby closing the rear end of the outer shell;

a hollow inner liner, having a front end and a rear end, the inner liner supported withing the hollow portion of the outer shell and positioned therein to provide an air passageway generally between the outer shell and the inner liner, the front end of the inner liner extending through the front end wall and the rear end of the inner liner being spaced a distance from the rear end wall;

an air inlet in the outer shell, spaced a distance from the rear end of the outer shell for admitting combustion air into the air passageway;

means for injecting fuel into the hollow portion of ment apparatus including an annular member havthe outer shell generally between the rear end of m f ti about its periphery to diff a the inner liner and the rear end wall; and

a noise abatement apparatus secured to the rear end of the inner liner and extending a distance therefrom, generally between the rear end of the inner liner and the rear end wall, the noise abateportion of the combustion air to substantially reduce the undesirable noise during the operation of the gas burner apparatus. 

1. A gas burner apparatus, comprising: a hollow outer shell having a front end and a rear end; a front end wall secured to the front end of the outer shell, thereby closing the front end; a rear end wall, having an opening formed therethrough, secured to the rear end of the outer shell, thereby closing the rear end; a hollow inner liner, having a front end and a rear end, the inner liner supported within the hollow portion of the outer shell and being spaced from the outer shell to form an air passageway between the outer shell and the inner liner, the front end of the inner liner extending through the front end wall and rear end of the inner liner being spaced a predetermined distance from the rear end wall; an air inlet formed in the outer shell and spaced from the rear end thereof for admitting combustion air into the air passageway; means for injecting fuel through the opening in the rear end wall and into the hollow portion of the outer shell, generally between the rear end of the inner liner and the rear end wall, the fuel and combustion air being mixed and burned generally within the hollow portion of the inner liner; a noise abatement apparatus, including an annular member having perforations about its periphery and, secured to the rear end of the inner liner and extending a distance therefrom generally between the rear end of the inner liner and the rear end wall, to diffuse a portion of the comBustion air thereby substantially eliminating undesirable noise during the operation of the gas burner apparatus; and a pilot flame protection apparatus, an annular member having perforations about its periphery secured to a portion of the rear end wall, the flame protection apparatus substantially encompassing the opening through the rear end wall to diffuse a portion of the combustion air thereby preventing the combustion air from blowing out said pilot flame.
 1. A gas burner apparatus, comprising: a hollow outer shell having a front end and a rear end; a front end wall secured to the front end of the outer shell, thereby closing the front end; a rear end wall, having an opening formed therethrough, secured to the rear end of the outer shell, thereby closing the rear end; a hollow inner liner, having a front end and a rear end, the inner liner supported within the hollow portion of the outer shell and being spaced from the outer shell to form an air passageway between the outer shell and the inner liner, the front end of the inner liner extending through the front end wall and rear end of the inner liner being spaced a predetermined distance from the rear end wall; an air inlet formed in the outer shell and spaced from the rear end thereof for admitting combustion air into the air passageway; means for injecting fuel through the opening in the rear end wall and into the hollow portion of the outer shell, generally between the rear end of the inner liner and the rear end wall, the fuel and combustion air being mixed and burned generally within the hollow portion of the inner liner; a noise abatement apparatus, including an annular member having perforations about its periphery and, secured to the rear end of the inner liner and extending a distance therefrom generally between the rear end of the inner liner and the rear end wall, to diffuse a portion of the comBustion air thereby substantially eliminating undesirable noise during the operation of the gas burner apparatus; and a pilot flame protection apparatus, an annular member having perforations about its periphery secured to a portion of the rear end wall, the flame protection apparatus substantially encompassing the opening through the rear end wall to diffuse a portion of the combustion air thereby preventing the combustion air from blowing out said pilot flame.
 2. The gas burner apparatus of claim 1 where the inner liner includes, a frusto-conical section converging toward the rear end thereof and a frusto-conical section converging toward the front end thereof; and wherein the outer shell is defined further as being shaped such that the inner liner and the outer shell are coaxially positioned.
 3. The gas burner apparatus of claim 1 wherein the rear end of the inner liner is defined further as being spaced a distance from the rear end wall, the distance being at least one-half the diameter of the hollow portion of the inner liner, generally adjacent the rear end thereof.
 4. The gas burner apparatus of claim 1 wherein the air inlet is defined further as being volute shaped to provide tangential combustion air into the air passageway.
 5. The gas burner apparatus of claim 1 wherein the noise abatement apparatus is defined further as extending a distance from the rear end of the inner liner, the distance being substantially equal to one-fourth of the distance between the rear end of the inner liner and the rear end wall.
 6. The gas burner apparatus of claim 1 wherein the noise abatement apparatus is defined further as being generally cylindrically shaped, the diameter of the outer periphery of the noise abatement apparatus being sized to be slid into the hollow portion of the inner liner, generally adjacent the rear end of the inner liner.
 7. The gas burner apparatus of claim 6 wherein the noise abatement apparatus is defined further to include: a plurality of stops, each stop being secured to a portion of the outer periphery of the noise abatement apparatus and extending a distance radially therefrom, each stop engaging a portion of the rear end of the inner liner to position the noise abatement apparatus in an assembled position within the hollow portion of the inner liner.
 8. The gas burner apparatus of claim 1 wherein the flame protection apparatus is defined further as extending a distance from the rear end wall generally toward the rear end of the inner liner, the distance being generally between 35 and 40 percent of the distance between the rear end of the inner liner and rear end wall.
 9. The gas burner apparatus of claim 1 wherein the flame protection apparatus is defined further as being generally cylindrically shaped, the diameter of the flame protection apparatus being approximately equal to 50 percent of the diameter of the hollow portion of the inner liner, generally adjacent the rear end thereof. 